Negative-pressure hydrocephalus in the course of a complex postoperative intracranial pressure disturbance: illustrative case

Abstract

Background: Negative-pressure hydrocephalus (NePH) is a rare clinical entity that presents on the background of ventriculomegaly with atypical symptoms. Its diagnosis is difficult, and some patients experience several shunt revisions until the proper solution is found.

Observations: The authors present a patient who developed acute deterioration due to iatrogenic NePH after surgery for a vertebral artery thrombosed giant aneurysm. The deterioration occurred after the insertion of a lumbar drain by which the authors intended to reduce a postoperative subcutaneous cerebrospinal fluid (CSF) collection. The drainage created an unexpected negative-pressure gradient in the CSF spaces, which resulted in NePH. Interventions, such as extraventricular drainage and blood patch, corrected the negative transmantle pressure and stabilized the patient's condition.

Lessons: Because the pathophysiology of NePH is theoretically considered to be caused by negative transmantle pressure, the intervention should be performed in order to deal with the coexistence of obstruction in the CSF pathways and a CSF leak. A blood patch would be an effective option in treating the CSF leak when the site of leakage is certain. This is the first case in which a blood patch was effectively applied in the treatment for NePH with a favorable outcome without any permanent CSF diversion.

Keywords: CSAS = cortical subarachnoid space; CSF = cerebrospinal fluid; CT = computerized tomography; ETV = endoscopic third ventriculostomy; EVD = external ventricular drainage; GCS = Glasgow Coma Scale; MRI = magnetic resonance imaging; NePH = negative-pressure hydrocephalus; POD = postoperative day; VA = vertebral artery; blood patch; low-pressure hydrocephalus; negative-pressure hydrocephalus.

Fig. 1.

A and B: CT scan before the operation and the MRI on POD 1 showed no change in the ventricular size. C: After starting lumbar drainage (LD) to treat the accumulating subcutaneous CSF, the patient’s consciousness became impaired (GCS score 6) and the CT scan showed prominent bilateral ventriculomegaly. D: Sagittal image of the same CT scan at the time of deterioration. Clear downward shift of the posterior fossa contents cannot be confirmed because of the presence of residual aneurysm portions and postoperative artifacts in the foramen magnum area. Significant posterior bony decompression of the craniovertebral junction is visible. Magendie foramen patency cannot be confirmed.

Fig. 2.

A: POD 2. Though the ventriculomegaly remained, the GCS score was 14 in the supine position. B: POD 4. After head elevation, the patient’s consciousness became impaired again (GCS score 6) and the CT scan showed further enlarged ventricles. C: POD 4. Following EVD, the scan revealed obvious pneumocephalus with the ventricular size reduced. The patient’s mental status recovered to slight disorientation (GCS score 14). D: POD 6. After a blood patch, the CT scan demonstrated normal- and stable-sized ventricles.